Bryan Stevenson grew up in a low-income African-American family on the eastern shore of Delaware. His racially segregated world offered him little hope of conquering realms beyond his town. But through effort and good fortune, Stevenson broke away to attend Harvard Law School.

Harvard Law graduates often decide to use the degree to earn a fortune inside a big firm representing banks and such. Not Stevenson. When he was 16 years old, his 86-year-old grandfather was murdered in Philadelphia. It seemed nobody outside Stevenson's family cared, especially law enforcement officials. That injustice, combined with a social conscience Stevenson developed at an early age, led him to represent defendants who had been treated unfairly — some of whom sat on death row, and some of whom were almost surely innocent.

"Just Mercy" opens in 1983. Stevenson is a law student completing an internship at the Southern Prisoners Defense Committee (now the Southern Center for Human Rights) in Atlanta, tasked with driving alone to a rural Georgia prison to meet with a death row inmate named Henry. Stevenson would not be conveying good news, and he worried that the inmate would curse him. Instead, the inmate accepted the bad news with equanimity, thanking Stevenson profusely for taking time to visit.

"In that moment, Henry altered something in my understanding of human potential, redemption, and hopefulness," Stevenson explains. From that day forward, Stevenson has devoted his life to helping exonerate imprisoned innocent inmates, to improving conditions on death rows and inside prisons in general and to changing laws and customs so that teenagers cannot be sentenced to life imprisonment after being tried as adults. He has worked for numerous other reforms as well. He has done so as a courtroom lawyer, a law professor and founder of the Equal Justice Initiative in Montgomery, Ala.

Because Stevenson's reform efforts within the criminal justice system are so diverse, his memoir jumps around from chapter to chapter, somewhat compromising effective narrative. There is a connecting thread, however — the wrongful murder conviction of Walter McMillian in Monroeville, Ala.

The case began in 1986 with the murder of a junior college student in a dry cleaning store where she worked. The student, Ronda Morrison, was pretty and Caucasian. Police found no obvious leads. So, under intense pressure, the local sheriff and his deputies and the prosecutor settled on McMillian, an African-American male who operated a small business, as the perpetrator. Law enforcement authorities lacked even an iota of credible evidence. Rather, they targeted McMillian at least in part because of his extramarital affair with a Caucasian woman.

Just Mercy

By: Bryan Stevenson.

Publisher: Spiegel & Grau, 352 pages, $28.

Review: Although the narrative jumps around in time a bit, Stevenson’s memoir is a powerful examination of the need for judicial reform.

COMING SUNDAY

Coming Sunday: A review of “Penelope Fitzgerald: A Life,” by Hermione Lee.

Nearly 20 years ago, I read a thick exposé of the McMillian case, "Circumstantial Evidence: Death, Life, and Justice in a Southern Town," by journalist Pete Earley. That book lionizes the then-young lawyer Stevenson. Earley's account shocked me so deeply that nothing in Stevenson's account of exonerating McMillian could have shocked me so deeply again.

Instead, Stevenson's book moved me because of his obviously brilliant mind, his bottomless compassion for the underdog and his successful championing of justice on so many fronts.

Steve Weinberg has written about the criminal justice system as a journalist since 1969.